HC/AC-forhold (hode mot mage)
Skriv inn svangerskapsuke, hodeomkrets og mageomkrets for å se HC/AC-forholdet, hvordan det står seg mot vanlige verdier, og en enkel vurdering av balansen. Kun til informasjon.
What is the HC/AC ratio?
It is the **head circumference divided by the abdominal circumference**, both in millimetres. It gives a simple measure of how head and abdomen size compare.
Which weeks does this tool support?
The calculator supports **weeks 18 to 42**. Values outside this are clamped to the nearest supported week before calculating the typical ratio.
What does “Balanced head and abdomen” mean here?
It means your HC/AC ratio is within about **one standard deviation** of the model’s typical ratio for that week, so the proportions are close to average in this model.
What if the result says “Head proportionally larger” or “Abdomen proportionally larger”?
It only means your ratio is more than one SD above or below the typical value in this model. Your care team will decide if that matters clinically based on full ultrasound findings.
Do I have to use mm?
Yes. The inputs and outputs are in **millimetres**. If your report is in cm, multiply by 10 before entering (for example 25.0 cm → 250 mm).
Does this replace ultrasound interpretation by my provider?
No. It is an educational helper for context only. Your provider interprets all measurements together (HC, AC, weight, fluid, Dopplers, history) and their judgement always comes first.